The molar mass of Na₂SO₄ -
2 x Na - 2 x23 = 46
1 x S - 1 x 32 = 32
4 x O - 4 x 16 = 64
total = 46 + 32 + 64 = 142 g/mol
the molarity of solution - 2.0 M
in 1 L of solution , 2.0 moles
Therefore in 2.5 L - 2 mol/L x 2.5 L = 5 mol
then the mass of Na₂SO₄ required = 142 g/mol x 5 mol = 710 g
Answer:
22.7%
Explanation:
Given that last year stock for company A was $7200
The stock for company B last year was worth $3510
Stock in company A decreased by 24%
This means the new value of stock for company A became;
(100-24)/100 *$7200
76/100*$7200
0.76*7200 =$5472
Stock in company B decreased by 20%
This means the new value of stock for company B became;
(100-20)/100 *$3510
80/100*$3510
0.8*$3510
$2808
Original investors stock value was = $7200+$3510 =$10710
New investors stock value is = $5472+$2808=$8280
Decrease in value of stock = $10710-$8280 =$2430
percentage decrease in stock value = decrease in stock/original value of stock *100%
=2430/10710 *100 =22.689
=22.7%
Answer:
Explanation:
First Question. Answer is: B. They are different.
For examle, balanced chemical reaction of forming water from hydrogen and oxygen:
2H₂ + O₂ → 2H₂O.
During chemical reaction no particles are created or destroyed, the atoms are simply rearranged from the reactants to the products.
Oxygen (element) has boiling point of -183°C and hydrogen has boiling point of -253°C. In this chemical change water (compound) is produced and it has new boiling point, boiling point of water is 100°C.
Answer:
Explanation:
1)The charge of one electron is given by
1 e = - 1.6 * 10-19 C
Then – 1 C = 1 e / ( 1.6 * 10-19 )
= 6.25 * 1018 e
So one-coulomb charge has 6.25 * 1018 electrons
2)Let q1 and q2 be two charges separated by a distance r
Then q1 = - 40 µC = - 40 * 10-6 C
And q2 = 108 µC = 108 * 10-6 C
